We Keep Coding

Using a dynamic variable for the key of an object literal [duplicate]

This question already has answers here:
How to use a variable for a key in a JavaScript object literal?
(16 answers)
Closed 4 years ago.
I have a series of variables that I would like to pass into an object and I need the left side key to be pulled from a dynamic variable. How would I go about doing this?
Here's an example:
var characteristic = 'color';
var value = 'green';
// Desired JSON output
var object = {
color: 'green'
}

like so:
var characteristic = 'color';
var value = 'green';
var object = {
[characteristic]: value
}
console.log(object);

Going through a object with a variable [duplicate]

This question already has answers here:
JavaScript object: access variable property by name as string [duplicate]
(3 answers)
Closed 6 years ago.
I guess I didnt really know how to ask this question for me to find an answer.
So I have three variables that are going to make this function do what it has to
function gatherDataForGeographic(ele) {
var $this = $(ele)
var $main_title = $this.find('.options-title'),
$option = $this.find('.option');
var arr = []
var reportAreas = reportManager.getReportAreasObject();
$option.each(function () {
var $this = $(this)
var $checkbox = $this.find('.checkbox');
var type = $this.data('type'),
index = $this.data('index');
if ($checkbox.hasClass('checkbox--checked')) {
console.log(reportAreas.type)
} else {
return true;
}
})
return arr;
}
//this will return an object that I need to index
var reportAreas = reportManager.getReportAreasObject();
//this will get the a key that i need from the object
var type = $this.data('type');
//this will give me the index I need to grab
var index = $this.data('index');
So what I am trying to do is go through the object based on the type(or key) from the option selected by a user
The problem...
It is looking for reportArea.type[index] and is not recognizing it as a variable and I keep getting undefined because .type does not exist.
Is there a way for it to see that type is a variable and not a key?

You can use dynamic properties in JS using the bracket syntax, not the dot syntax:
reportAreas[type]
That will resolve to reportAreas['whateverString'] and is equivalent to reportAreas.whateverString- reportAreas.type however, is a literal check for type property.

reportArea[type][index]
JavaScript objects are just key-value pairs and the dot syntax is just syntactic sugar for the array notation.
object['a']
and
object.a
Are the same thing, basically.

Jquery object assign to variable return undefined [duplicate]

This question already has answers here:
Convert a JavaScript string in dot notation into an object reference
(34 answers)
Closed 7 years ago.
Working SO code below:
var property_object_parse = jQuery.parseJSON('{"p1":{"TextElement":[{"yscale":"100","xscale":"100","shadow":"false","rotation":"","id":"#1_company name","text":"Company name","font":"Plantagenet Cherokee","size":"9","h":"0.16","w":"1.15","y":"0.3","x":"0.53","lock":"false","customize":"false","Alpha":"100","underline":"false","italic":"","blockName":"company name","caption":"Company name","textType":"Company name","bold":"false","colorspace":"DeviceRGB","colorcode":"rgb(1.00,1.00,1.00)","color":"16777215","hex_color":"","valign":"center","align":"left","sortorder":"0","inputformat":false,"format":false,"clippath":false,"inputrequired":false},{"yscale":"100","xscale":"100","shadow":"false","rotation":"","id":"#1_first name","text":"First name","font":"Plantagenet Cherokee","size":"7","h":"0.1","w":"1.14","y":"0.44","x":"2.3","lock":"false","customize":"false","Alpha":"100","underline":"false","italic":"","blockName":"first name","caption":"First name","textType":"First name","bold":"false","colorspace":"DeviceRGB","colorcode":"rgb(1.00,1.00,1.00)","color":"16777215","hex_color":"","valign":"center","align":"right","sortorder":"1","inputformat":false,"format":false,"clippath":false,"inputrequired":false},{"yscale":"100","xscale":"100","shadow":"false","rotation":"","id":"#1_last name","text":"Last Name","font":"Plantagenet Cherokee","size":"6","h":"0.11","w":"1.16","y":"0.56","x":"2.3","lock":"false","customize":"false","Alpha":"100","underline":"false","italic":"","blockName":"last name","caption":"Last Name","textType":"Last Name","bold":"false","colorspace":"DeviceRGB","colorcode":"rgb(1.00,1.00,1.00)","color":"16777215","hex_color":"","valign":"center","align":"right","sortorder":"2","inputformat":false,"format":false,"clippath":false,"inputrequired":false},{"yscale":"100","xscale":"100","shadow":"false","rotation":"","id":"#1_email","text":"Email","font":"Plantagenet Cherokee","size":"6","h":"0.1","w":"1.14","y":"0.69","x":"2.3","lock":"false","customize":"false","Alpha":"100","underline":"false","italic":"","blockName":"email","caption":"Email","textType":"Email","bold":"false","colorspace":"DeviceRGB","colorcode":"rgb(1.00,1.00,1.00)","color":"16777215","hex_color":"","valign":"center","align":"right","sortorder":"3","inputformat":false,"format":false,"clippath":false,"inputrequired":false},{"yscale":"100","xscale":"100","shadow":"false","rotation":"","id":"#1_phone","text":"Phone","font":"Plantagenet Cherokee","size":"6","h":"0.11","w":"1.14","y":"0.81","x":"2.3","lock":"false","customize":"false","Alpha":"100","underline":"false","italic":"","blockName":"phone","caption":"Phone","textType":"Phone","bold":"false","colorspace":"DeviceRGB","colorcode":"rgb(1.00,1.00,1.00)","color":"16777215","hex_color":"","valign":"center","align":"right","sortorder":"4","inputformat":false,"format":false,"clippath":false,"inputrequired":false},{"yscale":"100","xscale":"100","shadow":"false","rotation":"","id":"#1_street","text":"street","font":"Plantagenet Cherokee","size":"9","h":"0.17","w":"1.16","y":"0.95","x":"2.3","lock":"false","customize":"false","Alpha":"100","underline":"false","italic":"","blockName":"street","caption":"street","textType":"street","bold":"false","colorspace":"DeviceRGB","colorcode":"rgb(1.00,1.00,1.00)","color":"16777215","hex_color":"","valign":"center","align":"right","sortorder":"5","inputformat":false,"format":false,"clippath":false,"inputrequired":false}]},"p2":{"ImageElement":[{"type":"image","text":"Sample.png","blockName":"Back Logo","id":"#2_Back Logo","lock":"false","rotation":"0","h":"0.68","w":"0.69","y":"0.59","x":"0.41","valign":"bottom","halign":"left","clippath":false}],"TextElement":[{"yscale":"100","xscale":"100","shadow":"false","rotation":"","id":"#2_Company Name","text":"Company Name","font":"Plantagenet Cherokee","size":"9","h":"0.16","w":"1.16","y":"1.3","x":"0.24","lock":"false","customize":"false","Alpha":"100","underline":"false","italic":"","blockName":"Company Name","caption":"Company Name","textType":"Company Name","bold":"false","colorspace":"DevicaeRGB","colorcode":"rgb(1.00,0.00,0.00)","color":"16711680","hex_color":"","valign":"bottom","align":"center","sortorder":"0","inputformat":false,"format":false,"clippath":false,"inputrequired":false},{"yscale":"100","xscale":"100","shadow":"false","rotation":"","id":"#2_Tagline","text":"Sample Tagline","font":"Helvetica","size":"12","h":"0.18","w":"0.73","y":"1.52","x":"0.25","lock":"false","customize":"false","Alpha":"100","underline":"false","italic":"","blockName":"Tagline","caption":"Sample Tagline","textType":"Sample Tagline","bold":"false","colorspace":"DeviceRGB","colorcode":"rgb(1.00,1.00,1.00)","color":"16777215","hex_color":"","valign":"top","align":"left","sortorder":"1","inputformat":false,"format":false,"clippath":false,"inputrequired":false}]}}');
var selected_element = 'p1.TextElement[0].size';
console.log(property_object_parse.selected_element);
I am getting undefined when I try to get the value using variable. Is this correct way to access it?
See my jsfiddle here

property_object_parse is a real JavaScript object, so you can just use the member access syntax to access the value you are interested in directly:
console.log(property_object_parse.p1.TextElement[0].size);
Note that you cannot use a dynamic property path string like 'p1.TextElement[0].size', you would have to compile that in a way. For example, you could instead have an array of properties you are trying to access:
var selected_element = ['p1', 'TextElement', '0', 'size'];
var obj = property_object_parse;
for (var i = 0; i < selected_element.length; i++) {
obj = obj[selected_element[i]];
}
console.log(obj);
That has the same result as accessing it all directly as above with property_object_parse.p1.TextElement[0].size.

Can you evaluate a property name within a JS object? [duplicate]

This question already has answers here:
How to use a variable for a key in a JavaScript object literal?
(16 answers)
Closed 7 years ago.
I know that you can evaluate the value of a property inside of a JS object, like the following:
let object = {
value: 5+5
};
I am wondering if there is any possible way to evaluate the name of an attribute with JS, i.e. achieve the following:
let object;
object[5+5].value = "ten";
As something like:
let object = {
5+5: "ten"
};

Yes in ES2015, no in ES5, but first let's clear one thing up: that's JavaScript, not JSON.
In ES2015 (formerly known as ES6):
var something = "foo";
var object = {
[something]: "bar";
};
alert(object.foo); // "bar"
Inside the [ ] can be any expression you like. The value returned is coerced to a string. That means you can have hours of fun with stuff like
var counter = function() {
var counter = 1;
return function() {
return counter++;
};
};
var object = {
["property" + counter()]: "first property",
["property" + counter()]: "second property"
};
alert(object.property2); // "second property"
JSON is a serialization format inspired by JavaScript object initializer syntax. There is definitely no way to do anything like that in JSON.

Sure. Try this:
'use strict';
let object = {
[5+5]: "ten"
};
console.log(object); // Object {10: "ten"}

Creating object with dynamic keys [duplicate]

This question already has answers here:
How to use a variable for a key in a JavaScript object literal?
(16 answers)
Closed 8 years ago.
First off, I'm using Cheerio for some DOM access and parsing with Node.js. Good times.
Heres the situation:
I have a function that I need to create an object. That object uses variables for both its keys and values, and then return that single object. Example:
stuff = function (thing, callback) {
var inputs = $('div.quantity > input').map(function(){
var key = this.attr('name')
, value = this.attr('value');
return { key : value }
})
callback(null, inputs);
}
It outputs this:
[ { key: '1' }, { key: '1' } ]
(.map() returns an array of objects fyi)
I need key to actually be the string from this.attr('name').
Whats the best way to assign a string as a key in Javascript, considering what I'm trying to do?

In the new ES2015 standard for JavaScript (formerly called ES6), objects can be created with computed keys: Object Initializer spec.
The syntax is:
var obj = {
[myKey]: value,
}
If applied to the OP's scenario, it would turn into:
stuff = function (thing, callback) {
var inputs = $('div.quantity > input').map(function(){
return {
[this.attr('name')]: this.attr('value'),
};
})
callback(null, inputs);
}
Note: A transpiler is still required for browser compatiblity.
Using Babel or Google's traceur, it is possible to use this syntax today.
In earlier JavaScript specifications (ES5 and below), the key in an object literal is always interpreted literally, as a string.
To use a "dynamic" key, you have to use bracket notation:
var obj = {};
obj[myKey] = value;
In your case:
stuff = function (thing, callback) {
var inputs = $('div.quantity > input').map(function(){
var key = this.attr('name')
, value = this.attr('value')
, ret = {};
ret[key] = value;
return ret;
})
callback(null, inputs);
}

You can't define an object literal with a dynamic key. Do this :
var o = {};
o[key] = value;
return o;
There's no shortcut (edit: there's one now, with ES6, see the other answer).